Load carriers for use in overhead trolley conveyor systems



June 25, 1957 E. MULLEN ETAL 2,796,973

LOAD CARRIERS FOR USE IN OVERHEAD TROLLEY CONVEYOR SYSTEMS OtiginalFiled May 17, 1947 2 Sheets-Sheet 1 I r I a Q g \CQQIIH 2 I M I Q 1- 4/lb I T i I I I [ma l I l I I l I I I I I I I l I l I I I I I II I I II-I I I I I f" I I I I i I I I I l I l l I I I I I .I I I I I I l I I II I I I I I I I I i 7 l0 I 8 L .18

June 25, 1957 E. MULLEN ET AL 2,796,973

LOAD CARRIERS FOR USE IN OVERHEAD TROLLEY CONVEYOR SYSTEMS OriginalFiled May 17, 1947 2 She'ets-Sheet 2 P I T740 8 5 I v4 f /f1 SF ttesLOAD CARRIERS FOR USE INDVERHEAD' TROLLEY CONVEYOR SYSTEMS EdwardMullen, Detroit, Mich., and Ross Harris, Branson, Mo., assignors toMechanical Handling Systems, Inc., Detroit, Mich, a corporation ofMichigan 6 Claims. (Cl. 198177) This invention relates to overheadtrolley conveyors and more particularly to conveyor fixtures adapted tosupport a load at points longitudinally spaced along the conveyor trackand to be supported by a plurality of trolleys propelled along theconveyor track by a chain drive. This application is a division ofparent application Serial No. 748,704, filed on May 17, 1947, and nowPatent No. 2,664,993 and is directed to one of the nonelected speciesoriginally disclosed therein.

In providing carrying means of this type a number of problems areencountered in making provision for horizontal and vertical curves inthe conveyor track especially where each of the trolleys whichcontribute to the support of a single load is propelled by a commondrive chain.

The nature of such problems may be seen by referring to a typical casewherein four longitudinally spaced trolleys are used to support a singlerigid load, two adjacent trolleys being adapted to support each end ofthe load with a plurality of additional trolleys interposed between thetwo pairs of load supporting trolleys, and all of the trolleys beingpropelled by a common drive chain. If the relative motion of suchtrolleys be considered independently of any carrying means or loadattached thereto, the various types of movement which must be providedfor in such carrying means becomes apparent.

Taking first the case of a horizontal curve in the ttack, as the firstof the load supporting trolleys enters such curve, it is necessary thatsuch trolley pivot about a vertical axis relative to the followingtrolleys. As the first trolley rounds a curve the drive chain suspendedbetween the first two trolleys will form a chord cutting across the arcof the curve. Such chord line will be defined by the rear pivotal pointin the chain link which is attached to the first trolley bracket and theforward pivotal point in the chain link attached to the second trolleybracket. Since such pivotal points in the respective chain links areusually longitudinally spaced from the vertical axis of the trolleybrackets in question, a second chord line lying outside of the line ofthe chain intermediate the first two trolley brackets will be defined bythe vertical axes of the trolley brackets. The length of such secondchord line will be somewhat shorter than the distance between the sametrolleys axes on the straight section of track before entering the curvedue to the fact that as soon as the first trolley enters the curve,the'chain between the first two trolleys assumes a position other thanits most extended position. Therefore, if a carrying fixture supportedby the first two trolleys were such as to define a fixed distancebetween the trolleys, the first trol ley would not be free to follow thepath of the curve but would tend to beheld in a straight position by thetension developed in the drive chain.

Thus, it will be seen that any rigid carrying fixture suspended from thefirst two trolleys should include protnt 7 vision for permitting each ofthe trolleys to move closer to each other in rounding a horizontal curveas well as to permit each trolley to pivot about its vertical axisindependent of the other trolleys and independent of the position of thefixture between the first two trolleys.

As the trolleys continue around the curve, it will be seen that a seriesof short chord lines will be formed by the chain extending betweenadjacent trolley brackets and that a major chord line will be defined bythe forward and rear end of a load suspended from a point between thefirst two load carrying trolleys and at a second point between the lasttwo load carrying trolleys.

Since the drive chain attached to each of the trolley brackets followsmore closely the curved path of the conveyor track than the major chordline described above, it is apparent that the suspension connections atone end must be free to move closer to the suspension connections at theother end while the load is rounding a curve in the track by an amountequal to the difference in length between that of the major chord linementioned and the length of the chain between the points establishingsuch chord line. It is also apparent that during the rounding of suchcurve, the major chord line will extend in a horizontal direction bothdifferent from the line joining the first two load supporting trolleybrackets and that joining the last two load supporting trolley brackets.Thus, if any rigid form of member is used to divide the load between thefirst two or the last two load supporting brackets, provision must bemade for the pivotal movement of such rigid member about a vertical axisrelative to the fixture members which more directly support the load.

In the case of vertical curves, similar problems are encountered withrespect to changes in the relative distances between the forward andrear end supporting points as compared to the length of chain betweensuch points. In addition, in order that the individual bracket membersmay be free to assume a position normal to the surface of the trackthroughout such vertical curve, it becomes necessary to provide in theattachment to the 7 load carrying means a connection which permitspivotal movement of the individual brackets about a transverse axisrelative to the other brackets as well as to the load carrying means.

Furthermore, unless the load is to be permitted to swing freely in alongitudinal path relative to the load supporting brackets, a rigid formof carrying means must be provided which will maintain one end ot'theload in a substantially fixed position relativeto a load supportingbracket member associated with such end. To permit the swinging movementmentioned may be objectionable for a number of reasons includingpossible danger and damage incident thereto,- inconvenience where it isdesired to perform certain operations on the load as it is beingcarried, as well as additional space which would be required betweenadjacent loads to prevent one load from swinging into another as itstarted up or down a vertical curve.

On the other hand, it will be recognized that the provision of a rigidstructure for preventing such a swinging motion augments the difficultyin providing necessary freedom for the movements discussed above.

The embodiment disclosed herein incorporates the necessary freedom ofmovement discussed above while providing a fixed longitudinal positionfor the load relative to at least one of the supporting trolleys.

In general, it is the object of the presentinveirtion to provide acarrying fixture adapted to support an elongated rigid load, such as anautomobile body or chassis, from two longitudinally spaced points underan overhead corive'yor track, and to be supported by a plurality oftrolleys each of which is propelled along the conveyor track by a commondrive chain.

More specifically, it is an object of the present invention to providecarrying means of this general type which will permit- (a) The pivotalmovement of each load supporting trolley bracket about a vertical axisindependent of the other trolley brackets and of the load and loadcarrying fixture; and

(b) The pivotal movement of each load supporting trolley bracket in avertical plane passing through the conveyor track relative to the othertrolley brackets, load and load carrying fixture. Another object is toprovide carrying means incorporatmg provision for the relative movementsoutlined above which is simple, economical of construction anddependable.

These and other objects will appear more clearly from a detaileddescription of a particular embodiment of our invention and by referenceto the drawings forming a part hereof and wherein:,

Fig. 1 is a side elevation showing the general arrangement of thecarrying fixture adapted to convey a wheeled load carrying pallet alongan overhead conveyor track.

Fig. 2 is an end elevation of the carrying assembly taken along the line22 of Fig. 1.

Fig. 3 is an enlarged sectional view taken along the line 33 of Fig. l.

Fig. 4 is an enlarged sectional view taken along the line 4-4 of Fig. 1.

Fig. 5 is an enlarged fragmentary view of the coupling shown at thelower left-hand corner of Fig. 1.

Fig. 6 is a plan view of the coupling taken along the line 66 of Fig. 5.

Referring to Figs. 1 through 6, a load carrying fixture is shown whichis adapted to convey loads supported on wheeled pallets for convenientmovement of the loads along the floor of a plant while they are notbeing transported by the overhead conveyor system. This fixtureincorporates the use of round pipe as the major components of theframework including a single pipe member 93 extending over the completelength of the load and curved downward at the forward end 93a where itextends to the level of the load supporting pallet 94. Pivotallyconnected at 130 to the rear end of the pipe 93 an inverted U-shapedpipe member 95 is provided which extends downwardly to the level of therear end of the pallet 94.

Forward and rear trolley assemblies I and K are provided, the forwardassembly I fixing the longitudinal position of the carrying fixturewhile the rear trolley assembly K is free to move longitudinallyrelative to such fixture. As shown in Fig. 4, the hanger 96 in the reartrolley assembly K is provided with concave rollers 97 adapted to rollalong the curved surface of the pipe 93. Rigidly secured at the lowerforward end 98 of the pipe 93, as most clearly shown in Figs. 5 and 6,is a load supporting assembly comprising a bracket member 99 welded tothe pipe 98 which, in turn, supports the horizontal plate 100. A deeptapered notch 101 isprovided in the plate 100 and the bracket member 99is likewise provided with a recess 102 which together serve to guide andaccommodate the locking pin 103 provided in the forward end 104 of theload supporting pallet assembly. A locking member 105 is pivotallyattached to the bracket 99 as indicated at 106. This member is weightedat the forward end 107 in order to normally retain the rearward end 108in an upward position. When the pallet 94 is being loaded onto thecarrying fixture, the guide pin 103 is nosed into contact with thetapered surface 109 of the locking member 105 causing its rearward end108 to be depressed as the pin 103 moves into the recess 101, 102whereupon the rearward end 108 returns to its normal position, as shownin Fig. 5; locking the pin 103 in place. The rearward end 110 of thepallet may thereupon be 4 wheeled into alignment with the rear end ofthe fixture 95 which may then be swung into its supporting posi tion.The bracket member 111 rigidly secured to the lower tubular ends 112will then assume a supporting position beneath the end 113 of thepallet. Aligned bores provided in the bracket 111 and end 113accommodate locking pins 114. a.

It will be realized that the conveyor track 115 at loading points willbe positioned at a level relative to the floor level, such as willpermit the ends 116, 113 of the pallet to overlie respectivelysupporting plate 100 and supporting brackets 111 while the wheels 117 ofthe pallet are in supporting contact with the floor. As the conveyorfixture moves along such level with the pins 103, 114 in their properposition, the pallet 94 will be drawn along the floor, and as thefixture moves to a higher level, the plate 100 and brackets 111 willmove into supporting engagement with the ends of the pallets 116, 113,thereupon lifting the pallet and load carried thereon off of the floor.

As shown in Fig. 2, guide trolleys 118, 119, together with auxiliaryguide tracks 121 are provided to prevent lateral swinging of the loadthroughout any desired portion of the conveyor line. 1

Necessary freedom of movement of the trolley assemblies J and K and ofthe individual trolleys is accomplished through the pivotal connectionsshown most clearly in Fig. 3 providing freedom of movement aboutvertical, transverse, and longitudinal axes. Thus, relative pivotalmovement between individual trolleys 122 and spanning element 123 abouta vertical axis is provided by a pivotal connection at 124; between thespanning element 123 and the depending swivel element 125 about atransverse axis by a pin connection at 126; between the swivel element125 and hanger element 127 about a vertical axis by a swivel connectionat 128; and between the U-shaped extension 129 of the hanger element 127and the tubular member 93 about a longitudinal axis by thelongitudinally extending semi-cylindrical bearing surface of the Uextension 129.

While a satisfactory embodiment incorporating the essential features ofthis invention has been described in detail, it will be recognized thatnumerous changes in the detailed construction are possible withoutdeparting from the scope of the invention as set forth in the appendedclaims.

We claim:

1. An overhead conveyor system comprising an overhead conveyor track,longitudinally spaced, chain driven load supporting trolleys adapted totravel along said track, a carrier for rigid longitudinally extendingloads suspended from at least twoof said trolleys, said carrier having arigid member extending longitudinally between said supporting trolleys,connecting means fixing the longitudinal position of said memberrelative to one of said trolleys, connecting means accommodating freerelative longitudinal movement between said member and another of saidtrolleys, each of said connecting means including a vertical axis pivotpermitting swivel movement of each trolley relative to said member, saidmember having an integral depending portion at one end adapted to engageone end of a rigid load, and a depending member swivelly connected alonga transverse axis to the other end of said first member, thelower end ofsaid latter depending member being adapted to swing into position forengaging the other end of said rigid load.

2. A rigid load conveying means as set forth in claim 1 wherein saidfirst depending portion extends downwardly to a load engaging pointcentrally disposed under said conveyor track, and wherein said pivotallyconnected depending member is in the form of a yoke having load engagingportions extending downwardly to transversely spaced points on eitherside of the centerline of said conhead conveyor track, longitudinallyspaced, chain driven load supporting trolleys adapted to travel alongsaid track, a load carrier suspended from at least two of said trolleys,said carrier having a rigid member extending longitudinally between saidsupporting trolleys, connecting means fixing the longitudinal positionof said member relative to one of said trolleys, connecting meansaccommodating free relative longitudinal movement between said memberand another of said trolleys, each of said connecting means including avertical axis pivot permitting swivel movement of each trolley relativeto said member, said longitudinally extending member having an integraldepending portion extending downwardly to a load engaging level, adepending member connected to the other end of said longitudinallyextending member also extending downwardly to a load engaging level, anda wheeled load pallet adapted to be alternately engaged and carried bysaid depending elements of said carrier or to be deposited at floorlevel and disengaged from said carrier for independent movement alongthe floor.

4. Conveying means as set forth in claim 3 wherein one of said dependingelements extends down to a pallet engaging point centrally located belowthe conveyor track, and wherein the other depending element is in theform of a yoke extending downwardly to transversely spaced palletengaging points on either side of said conveyor track.

5. Conveying means as set forth in claim 3 wherein one of said dependingelements extends down to a pallet engaging point centrally located belowthe conveyor track,

and wherein the other depending element is in the form of a yokeextending downwardly to transversely spaced pallet engaging points'oneither side of said conveyor track, said central depending element beingprovided with a pallet supporting member and automatic latching meansfor engaging said pallet when moved along the floor to a loadingposition.

6. Conveying means as set forth in claim 3 wherein one of said dependingelements extends down to a pallet engaging point centrally located belowthe conveyor track, and wherein the other depending element is in theform of a yoke extending downwardly to transversely spaced palletengaging points on either side of said conveyor track, said centraldepending element being provided with a pallet supporting member andautomatic latching means for engaging said pallet when moved along thefloor to a loading position, said second depending element beingpivotally connected along a transverse axis to said first longitudinallyextending member and being provided at either lower end with a palletsupporting member adapted to be swung under the end of said pallet whenmoved to a loading position, connecting means being provided to locksaid latter supporting elements in supporting position under the end ofsaid pallet.

References Cited in the file of this patent UNITED STATES PATENTS1,417,528 Irish et al. May 30, 1922 1,769,134 Haif July 1, 19302,527,922 Falkner Oct. 31, 1950

